The American policy of containing communism led to the Korean War and later to the Vietnam War because it committed the United States to resisting communist expansion. These wars were fought for that purpose.

The containment policy said that the United States would try to prevent communism from expanding. The US would not directly try to overthrow existing communist regimes like that of the Soviet Union. However, it would try to prevent any country that was not already communist from becoming communist.

This led the US to become involved in the Korean War. North Korea invaded South Korea with the intention of reuniting the country under communist rule. That would have spread communism into a country (South Korea) where it did not already exist. In addition, it might have threatened such countries as Japan. Therefore, the US entered the Korean War to prevent communist expansion.

The same thing happened in Vietnam. The US entered that war to prevent South Vietnam from being controlled by the communists. This turned into the country’s longest war because the communists were not easily defeated. The US felt that it had to keep trying to contain communism and so it kept on fighting, making this the longest war in US history.